This Application claims the benefit of Korean Application No. P2000-56211 filed on Sep. 25, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a flat panel fluorescent lamp, and more particularly, to a flat panel fluorescent lamp providing high luminance as a light source.
2. Discussion of the Related Art
A cathode ray tube (CRT), one of display devices, is mainly used in monitors of information terminals and measuring instruments including a television. However, it was difficult for the CRT to actively adapt to miniaturization and lightweight due to its weight and size.
An LCD device having a thin and small size has been actively developed in order to substitute for such a CRT. Recently, the LCD device is used as a flat panel display device. Thus, a demand of the LCD device is increasing consistently.
Such an LCD device is based on an electric-optical characteristic of a liquid crystal injected within a panel. Unlike a plasma display panel (PDP) and a field emission display (FED), the LCD does not emit light in itself. In order to view a picture displayed in an LCD panel, a separate light source, i.e., a back light assembly for uniformly irradiating light into the display panel of the picture is required.
Conventionally, a tubular cold cathode fluorescent lamp has been used as a back light assembly for the LCD. The lamp may have a straight-line shape or may be bent to have an L shape, U shape, or W shape, depending on its application.
Such a back light assembly is divided into an edge light type and a direct type depending on the position of the light source against a display area. In the direct type back light assembly, a fluorescent lamp is mounted on the lower portion of a liquid crystal panel and a light-diffusion plate is mounted between the fluorescent lamp and the liquid crystal panel. In the edge light type back light assembly, light generated from the fluorescent lamp mounted at the side of the liquid crystal panel is distributed over the whole LCD screen using a transparent light-guiding plate.
A related art light-emitting lamp for an LCD will now be described with reference to FIG. 1 illustrating a structure of a related art direct type back light assembly.
As shown in FIG. 1, the related art direct type back light assembly includes a liquid crystal panel 11, a plurality of fluorescent lamps 13, and a light-diffusion plate 15. The fluorescent lamps 13 are formed at the rear of the liquid crystal panel 11 in a straight-line shape, or in a U shape or W shape, so as to supply light to the liquid crystal panel 11. The light-diffusion plate 15 is interposed between the fluorescent lamps 13 and the liquid crystal panel 11 and disperses light emitted from the fluorescent lamps 13 to uniformly emit the light.
In the aforementioned direct type back light assembly, light is generated from a light source mounted below the liquid crystal panel 11 to face the liquid crystal panel 11 and enters into the liquid crystal panel.
Meanwhile, FIGS. 2A and 2B show structures of a related art light-guiding plate type back light assembly. FIG. 2A shows a structure of a back light assembly for a notebook PC while FIG. 2B shows a structure of a back light assembly for a monitor.
Referring to FIG. 2A, the back light assembly for a notebook PC includes a lamp assembly consisting of a liquid crystal panel 21, a light-emitting lamp 23, and a lamp reflecting plate 25. The light-emitting lamp 23 and the lamp reflecting plate 25 are formed at the rear edge of the liquid crystal panel 21. The back light assembly further includes a light-guiding plate 27 mounted to uniformly emit light generated from the light-emitting lamp 23 and the lamp reflecting plate 25 on the entire surface of the liquid crystal panel 21. A reflecting plate 29 is attached at the rear of the light-guiding plate 27. A sheet such as a prism 31 and a light-diffusion plate 33 is mounted between the light-guiding plate 27 and the liquid crystal panel 21 to condense and diffuse the light generated from the light-guiding plate 27. The light-guiding plate 27 is inclined at the rear to have a thick thickness toward the lamp assembly. The light-emitting lamp 23 is a cold cathode tube fluorescent lamp or a hot cathode tube fluorescent lamp and converts an electrical energy to an optical energy by a sealing gas. At this time, the emitting light is ultraviolet light. It is necessary to convert the ultraviolet light to visible light because the ultraviolet light cannot be seen by eyes of a human being. To this end, an inner wall of a glass tube of the light-emitting lamp 23 is coated with a phosphor 35.
In the aforementioned light-guiding plate type back light assembly, the lamp reflecting plate 25 is separately attached regardless of the light-diffusion plate 33 or the reflecting plate 29 to reflect light emitted to the rear except for the front of the lamp upon the side of the light-guiding plate 27.
Meanwhile, referring to FIG. 2B, unlike the back light assembly of FIG. 2A, a lamp assembly consisting of a light-emitting lamp 23 and a lamp reflecting plate 25 is mounted at both rear edges. The back light assembly of FIG. 2B is similar to that of FIG. 2A other than the lamp mounted at both sides of a light-guiding plate 27 having a uniform thickness.
However, the related art fluorescent lamp has several problems in view of a recent tendency that an LCD is applied to monitors, TVs, and multimedia as well as a notebook PC.
First of all, it is difficult to obtain high luminance suitable for a large size screen. Also, since a light source unevenly exists, a display quality is degraded. In addition, it is difficult to obtain a thin and small size lamp when a display panel is large. Further, when an optical element that enhances optical efficiency, such as a prism sheet, is used for a TV or multimedia, a light-emitting angle characteristic is not good enough to be used in variety of areas.
Accordingly, the present invention is directed to a flat panel fluorescent lamp having high luminance that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a flat panel fluorescent lamp having high luminance, in which a thin and small size can be obtained and a uniform light source is provided to satisfy a wide light-emitting angle and high luminance.
Additional features and advantages of the invention will be set forth in the description, which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a flat panel fluorescent lamp includes first and second glass substrates coupled with each other, at least one discharge path formed in the second glass substrate, and at least one pair of electrodes formed at the discharge path.
In another aspect of the present invention, a liquid crystal display having a flat panel fluorescent lamp includes a liquid crystal panel having a liquid crystal filled therein, a light diffusion plate coupled to the liquid crystal panel, first and second glass substrates coupled to the liquid crystal panel, at least one discharge path formed in the second glass substrate, and at least one pair of electrodes formed at the discharge path.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.